I don't know anything about that particular course, but since you have so much time, I think you can adequately prep for Quant on your own, at least for the next several months. I'd begin my using a basic Math review book, such as Kaplan's. Then move on to MGMAT Number Properties.
The best thing about GMAT Quant is that is tests a reliably finite number of concepts. Learn the concepts one-by-one and it makes the math seem a lot easier! I'd start with these 10 concepts, since they are among the most challenging and you may need more time on them:
1. Number Properties. The properties of odds and evens, integers, fractions, positives, and negatives will all appear in various questions on your GMAT test. Don't ever make assumptions about unknown variables. Unless you are told otherwise by the limitations in the question, variables can be negative integers, negative fractions, zero, positive fractions, or positive integer. You may need to Pick Numbers from multiple categories before you can arrive at a correct answer.
2. Inequalities. Some of the hardest Data Sufficiency questions on the GMAT will involve inequalities. Usually they are combined with Number Properties to make them even more challenging. Remember that when you multiply or divide by a negative number, you must reverse the direction of the inequality.
2. Coordinate Geometry. Not only will you need to know the standard equations for a line, parabola, and circle, but also you will need to memorize the distance formula, the midpoint formula, the slope formula, the relationship between slopes and the different quadrants, properties of parallel, perpendicular, vertical, and horizontal lines, as well as the quadratic formula/discriminant. Coordinate Geometry is a big concept on the GMAT, so don't put it off!
3. Plane Geometry. Triangles are tested a lot on the GMAT. You should know the Pythagorean Theorem, Triangle Inequality Theorem, the special right triangles: 45-45-90 and 30-60-90, as well as the properties of isosceles and equilateral triangles. Other plane geometry concepts to review include angles, circles, and polygons. Make sure you know how to find the perimeter and area of all shapes, and be comfortable dividing irregular shapes into manageable pieces.
4. Rates & Work. The classic need-to-know formula on the GMAT is D = R x T, Distance = Rate x Time. This concept is most-tested in Word Problems.
5. Probability & Combinatorics. The probability of an event occurring is the desired outcomes/total possible outcomes. The probability of two events occurring together is the product of the two probabilities. Memorize the combination and permutation formula and do a little digging around the web to tackle some harder Combinatorics questions.
6. Ratios and Proportions. A ratio is a relationship between two things. Given a ratio and one "real world" number, you can always set up a proportion to solve for the other missing "real world" number. Sometimes you will need to do this for similar triangles in Geometry, and sometimes in algebraic word problems.
7. Percents. For percent question with unknown starting values, always pick 100. Make sure to review profit and interest concepts and know the formulas for simple and compound interest. Remember to calculate percent questions carefully, step by step, especially in long Problem Solving questions.
8. Statistics and Sets. Although standard deviation is tested less-often, you will need to know generally how it is calculated, how it relates to the mean, and what percent of a group falls within each standard deviation. The GMAT will test more often mean, median, mode, range, domain, and other questions involving sets. Make sure you know how to use a Venn diagram.
10. Systems of Equations. You will need to be able to solve for a system of equations. Remember the "n equations with n variables" rule. If you have 2 variables, x and y, then you will need 2 equations with those 2 variables to solve for both. Familiarize yourself with Substitution and Combination.
Good luck!
